Liglaurates A–E, cytotoxic bis(lauric acid-12yl)lignanoates from the rhizomes of Drynaria roosii Nakaike

Five undescribed bis(lauric acid-12-yl)lignanoates, liglaurates A-E, along with the known methyl and glyceryl 12-caffeoyloxylaurates were isolated from the rhizomes of Drynaria roosii Nakaike. Their structures including absolute configurations were determined by HRESIMS, NMR techniques, and ECD calculation. Liglaurates A-D were isolated as the racemates, among which (±)-liglaurate A and (±)-liglaurate B were synthesized by a metal-mediated oxidative coupling reaction and further resolved as the enantiomerically pure compounds. Liglaurates (+)-A, (-)-A, (+)-B, (-)-B, (±)-C and (±)-D exhibited remarkable cytotoxic activities against HeLa cell line, with the IC50 values of 0.11 ± 0.02, 0.24 ± 0.01, 0.02 ± 0.00, 0.13 ± 0.02, 0.34 ± 0.07 and 0.17 ± 0.01 μM, respectively.